Watermass Distribution and Fluxes in the FRAM Strait for the Period 2007 – 2014

An analysis of the output of the Navy's Arctic Cap Nowcast-Forecast System (ACNFS) has been performed. The ACNFS model is a pan-arctic model covering the domain from in 40N-90N, 0-360E. For the current analysis, we extracted the FRAM domain 20W-20E, 74N-82N. In this region the ACNFS has an E-W grid resolution of 0.08°, and a N-S resolution of 0.04°. The analyzed FRAM domain has been split into 3 parts: (1) a central (narrow) portion of the Straits, with extent 10W-15E and 77N-80N; (2) a southern inflow region, with extent 15W-18E and 74N-77N; and (3) a northern outflow region, with extent 20W-15E and 80N-82N. The main focus of this analysis is on the central portion, where the dominant transport currents of the southward flowing cold East Greenland Current (EGC) and the northward moving warm West Spitsbergen Current (WSC) interacting with increased shear and turbulent mixing. For this analysis period, there is an upward trend in the August maximum temperatures, located near (78N, 9E) and in the 0-40m depth layer, from 5.4 °C (in 2008) to 7.0 °C (in 2014). There is a similar trend in the August peaks of the velocities (a) southward in the EGC, from -40.0 cm/s (in 2009) to -54.0 cm/s (in 2014); and (b) northward in the WSC, from 12.0 cm/s (in 2009) to 17.0 cm/s (in 2014).

The watermass analysis focuses on the deeper waters, since in the past these have not been studied as heavily as the surface Atlantic Water (AW). An initial examination reveals the presence of AW from 100m to 900m depth, all along 70E. Below 900m, several subclasses of Deep Water (DW) extend down to the bottom (at 3500m). The dominant 3 subclasses are: Eurasian Basin Deep Water (EBDW) from 1300m down to 2100m; Canadian Basin Deep Water (CBDW) from 2100 – 2400m; and Arctic Ocean Deep Water (AODW) from 2400m to 3500m. Missing are the DWs of the Greenland and Norwegian Seas, which had difficulty penetrating the Strait; special effort was made to study the entrance region for this reason.